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When goldfish are preparing to lay eggs (otherwise known as “spawning”) the goldfish is said to be pregnant. If you believe your goldfish may be preparing to spawn, there are a several ways to find out. First, try to figure out whether or not the conditions are right for your fish to spawn. Then, try to observe "pre-spawning" behaviors in both your male and female fish. Although it is rare, it is possible to purchase a pregnant goldfish. Otherwise, your fish will only become pregnant if there are both male and female fish present.

Steps

Part 1

Checking the Conditions

1

Find out if your fish is female. The best way to find out the sex of your goldfish is to ask when you buy the fish, or to consult a vet. That said, females goldfish typically have plump bodies. When viewed from above, you can usually notice fuller bellies on the females, and slender midsections of the males. Also, the female pectoral fins (located just behind the gills) are shorter and rounder than those on males.[1]

Additionally, goldfish will generally not lay eggs until they at least one year old.

2

Consider the time of year. If your goldfish is kept outside, it will only spawn during the spring or early summer. If your goldfish has always been kept inside, it could spawn at any time of year. Think about what season it is when determining if your outdoor goldfish is pregnant.[2]

3

Check your water temperature. Goldfish are most likely to breed in water that is around 68 °F (20 °C). If you believe your goldfish may be preparing to spawn, check the temperature of your water to see if the temperature right.[3]

Part 2

Looking for Pre-spawning Behaviors

1

Look for spawning tubercles on your male goldfish. When your male goldfish are ready to spawn, they will develop tiny white bumps known as “spawning tubercles” around their heads, gill covers, and pectoral fins. If you notice these white spots on your male fish, there is a greater chance that your female fish may be pregnant.[4]

Spawning tubercles may be hard to see. If you do not see these, it doesn’t mean that your fish isn't pregnant.

2

Notice male goldfish chasing female goldfish. When they are preparing to spawn, the male fish may chase the female ones, in a dance sometimes called the “spawning chase.” In many cases, this behavior is more obvious than spawning tubercles (which can be hard to see).[5]

3

Pay attention to your goldfish’s activity level. When goldfish are about to lay eggs, they usually start to move more sluggishly. Take note if your goldfish is moving slowly or seems to have trouble getting around.[6]

You may also notice your goldfish “nesting,” or spending most of the time hiding near shelters or plants.

4

Notice if your fish refuses food. When are fish are preparing to spawn, they will sometimes refuse food. If your goldfish isn't eating as much, it is possibly that they may lay eggs soon.[7]

5

Note the size of your goldfish’s body. Female goldfish are generally a bit rounder than male goldfish. When your female goldfish is about to lay eggs, the size of their belly may grow even larger, and stick out a bit.[8]

Just like the spawning tubercles, in some fish this can be quite noticeable, yet in others you may not see it at all.

Goldfish don't get pregnant that way; all fertilization happens outside. The female will spray her eggs and the male will spray sperm on them to fertilize them. The eggs will simply attach to any surface they land on.

What if the fish is lying on its side and then starts to move when I come near and goes up to the surface?

wikiHow Contributor

Community Answer

If your fish is on its side, it sound like a swim bladder issue. At this stage, it is unlikely there is anything you can do to help if your fish is floating. Try changing the water and reducing the water level see if this helps a bit.

One of my fish is starting to look fatter than usual, also another one died the day before I noticed this. Does this mean she's pregnant?

wikiHow Contributor

Community Answer

Goldfish don't get pregnant, as they are egg bearers. However they will increase in size when ready to lay. If your goldfish are getting fat and then dying, this is more likely a case of dropsy rather than pregnancy.

If you don't want them, leave them with the parents; they will eat them. If you do, get a new tank setup with a sponge filter, and start hatching brine shrimp. Give the baby goldfish the brine shrimp until they are big enough to accept regular baby goldfish food.

Article Info

This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. Together, they cited information from 8 references. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article meets our high standards.